Yes, the issue here is the familiar, "define your terms."

The true bonk, as described in the literature is not a transient drop in blood sugar which can be remedied by eating on the bike. The true bonk is the complete loss of all glycogen, both liver and muscle, then the drop in blood sugar which inevitably follows. This feels indescribably bad. The feeling is bad enough that people on historical death marches would rather be shot by the side of the road than continue. It becomes impossible for even the fittest cyclist to hit over 16 mph on the flat, and even that feels horrible.

There are also partial bonks, either liver or muscle, but not both. When we sleep, our brains use up almost all the glycogen stored in the liver, however our muscle glycogen remains the same as it was when we went to bed. If one gets up and without ingesting adequate carbs and then attempts a strenuous ride for long enough - 50 miles should do it, one will run out of liver glycogen. One rather loses the will to ride and gets a bit dizzy. Of course if one were in ketosis, that wouldn't happen, but OTOH, neither would the strenuous ride. Muscle glycogen will still be mostly there, so that's not a full bonk, just a rather awful feeling, but the cranks still go around. Been there, done that, but I don't think I've ever bonked my muscle glycogen and not the liver. Maybe, hard to say. I've slowly climbed many a hill all by myself toward the end of a fast group ride, but I didn't feel bonked.

1) I think I have had a couple true bonks. The first was on a double metric on which I rode the first 65 miles on the front with a couple riders fitter and stronger than I, riding all the hills near my anaerobic limit. I cramped so badly at that coffee break that I was rolling on the ground, well actually under the table. When we got going again I hung on the back for another 20 miles or so and then I was just gone. I had to soft pedal the rest of the way back, barely hitting 15 on the flat, whereas I was hitting 25 here and there during those first 65 miles. I stayed conscious and upright but that was it. I kept drinking my sports drink. That kept me going, but that's all. One can't replace glycogen on the bike.

2) Another time, I was just not eating enough on a solo century. At about the 50 mile mark, I felt really bad and had to stop. I sat in a ditch and watched the world spin around me. I ate a whole Clif bar, waited about 15 minutes and continued just fine. That was not a bonk, just really low BS.

Back to the OP, example 1 is NOT good training practice. One is going to be really tired and out of it for a couple days. Example 2 is just normal stupidity, no real problem, felt fine after the ride, but not good training practice either.

Riding an hour or two in the morning without eating can be good training, though it's limited training.. One will be training one's fatty acid transport mechanism, but the muscles and aerobic system not so much.